An electroacoustic transducer of the type defined in the opening paragraph and known to the applicant has been obtained as the result of the development of a new electroacoustic transducer by the applicant and is described in Austrian Patent Applications A 367/93 and A 368/93 both filed on Feb. 26, 1993 (herewith incorporated by reference).
In the transducers known to the applicant the partition wall and the mask wall are connected to one another in an acoustically sealed and mechanically rigid manner by means of an adhesive joint in a peripheral area of the mask wall. The adhesive joint is only very thin so that the two adjacent walls, i.e. the partition wall and the mask wall of the transducer, adjoin one another almost directly. The mask wall is formed by a flange of a pot of a magnet system of the transducer, which pot imperviously closes the first space of the transducer at the location of the back of the partition wall, which space extends through the central opening in the partition wall, so that in the known transducer the first space, which is situated partly between the diaphragm and one side of the partition wall, and the second space, which is situated at the other side of the partition wall, communicate with one another only via the acoustically active passages formed by the coincident openings in the partition wall and in the mask wall and for the remainder are wholly acoustically isolated from one another. The two spaces each form an acoustic capacitance and the acoustically active passage formed by two coincident openings in the two walls each form an acoustic inductance and an acoustic resistance arranged in series with this inductance, the essential part of each passage being formed by the opening having the smaller cross-sectional area, which determines the magnitude of the inductance and the magnitude of the series resistance. The magnitude of the series resistance is determined by the cross-sectional area and also by length, in the direction of the transducer axis, of the opening having the smaller cross-sectional area. However, the length of such an opening is relatively limited for reasons of production, so that altogether only an acoustic series resistance of comparatively small value is obtained. The two spaces in conjunction with the acoustically active passages between the spaces form two so-called Helmholtz resonators of which the resonance characteristics and hence the resonance step-ups are determined by the values of the acoustic capacitances and by the values of the acoustic inductances and series resistances formed by the passages. With the transducer known to the applicant it has now been found that as a result of the comparatively small values of the acoustic series resistances attainable with the openings of small cross-sectional area the Helmholtz resonators have a comparatively high Q factor and the resonators therefore have only a small damping, so that their resonance step-ups are comparatively pronounced, which leads to a rippled frequency response of the transducer.